Rewrite ${((9^{-10})(5^{-12}))^{7}}$ in the form ${9^n \times 5^m}$.
Solution: ${ ((9^{-10})(5^{-12}))^{7} = (9^{(-10)(7)})(5^{(-12)(7)})} $ ${\hphantom{ ((9^{-10})(5^{-12}))^{7}} = 9^{-70} \times 5^{-84}} $